This invention relates to a tire and rim combination having run-flat capabilities. The invention is directed to the problem of providing a tire and rim combination which will permit the elimination of the spare tire in a vehicle.
In recent years much emphasis has been placed on programs to provide tires with run-flat capabilities. This emphasis is a direct result of the energy shortages, both actual and predicted, that are presently a major concern of our society. One of the energy conservation matters that is being investigated is the elimination, or substitution, of the spare tire in vehicles. Pneumatic tires are comprised of several petroleum-based components so that a real conservation can be realized by the elimination of the spare tire. The resultant decrease in vehicle weight will also save gasoline.
The spare tire elimination proposals necessarily include that the tires on the vehicle have the capability of running flat when a tire problem occurs so that the vehicle may be driven to a lace of safety for the proper repair or replacement. Surveys have shown that 90% of the time a motorist is within 12 to 15 miles of some facility which can assist in any tire-related problems.
In addition to the capabilities set out above, a run-flat system must provide a tire and rim structure that has sufficient stability in its run-flat condition to permit the automobile to be driven safely to the repair facility. The system should also have the capability of preventing further injury to the tire in its run-flat operation so that the tire may be repaired and will not be lost by its run-flat operation.
One of the primary drawbacks of prior run-flat systems which contain internal crutch type members in the air chamber defined by the tire and rim is the complexity of such members. The combination of this invention is simple from the structural and installation aspects and is inexpensive. It requires no complex metal bolting operations.
Another major drawback of prior systems is the mounting and dismounting difficulty that these systems entail. The prior internal crutch type systems have required cumbersome and expensive mounting procedures that have made these systems unattractive from an economic and servicing convenience standpoint.
A further drawback of prior systems has been the necessity for special tires and particularly for special rims with unique features (such as split rims) so that conventional, standard tires and rims would not be workable in the prior systems. This represents a major disadvantage of prior systems as it makes all existing rims obsolete.
A further drawback of prior crutch type systems is the additional weight that these systems add to the tire and rim combination. The present invention is simple and lightweight compared to these prior systems.
In the present invention the performance requirements set out above are realized and the drawbacks set out above are overcome. This invention comprises a tire and rim combination having a run-flat support system located in the air chamber defined by the tire and rim. This run-flat support system is comparised of an annular, pneumatic tube member mounted in the drop center area of the rim and a rigid, or semi-rigid, ring member riding on the tube and located so that it will contact only the tube member, not the tire sidewalls or rim, when the combination is operated under normal operating conditions and will contact only the tube member and the inner periphery of the tread area of the tire when the combination is run flat. Due to this lack of contact of the ring member with the tire bead or sidewall areas or the rim during the normal or run-flat operations, the ring is characterized as "free-floating".
The concept of having a pneumatic tube located between the bead bundles of a pneumatic tire has been taught by U.S. Pat. Nos. 1,215,717; 1,626,514 and 2,224,066. These teachings also disclose an annular protective member located axially outwardly of the pneumatic tube. The structure of the present invention is distinguishable from these references in that the ring member of this invention contacts only the tube during normal operation of the combination and contacts only the tube and the inner periphery of the tread portion of the tire when the tire is run flat. In the structures of these references the ring member is connected to or in contact with the rim flange or the tire bead and is, therefore, not free-floating.
The structure of this invention, due to the "free-floating" nature of the ring member and the support of the ring member by the pneumatic tube member, permits the run-flat support system to act as a shock absorber when the tire is run flat, cornered hard or bottoms-out. This feature minimizes the transmission of shocks or these type to the rim and to the vehicle itself. This feature is not present in these prior teachings due to the fact that the protective ring member of the prior teachings is tied into or in contact with either the tire or rim or both.
It is an object of this invention to have a tire, rim and run-flat support system combination that will permit the tire to be operated in a run-flat condition without damage to the tire.
It is a further object of this invention to have a tire, rim and run-flat support system combination that has sufficient stability when the tire is in its run-flat condition to permit safe operation and handling of the vehicle to a location where assistance may be obtained.
It is a further object of this invention to provide a tire, rim and run-flat support system combination wherein standard tires and rims may be utilized.
Another object of this invention is to provide a tire, rim and run-flat support member system combination that is simple to manufacture and lightweight so that an excessive amount of heat will not be generated by the system.
Another object of this invention is to combine a tire, rim and run-flat support member system combination that permits easy mounting and dismounting of the tire.